lecture12_C

Report
BME 301
Lecture Twelve
HPV Testing


The DNAwithPap Test is FDA-approved for
routine adjunctive screening with a Pap
test for women age 30 and older.
Digene

http://www.digene.com
http://www.digene.com/PapX
YLC-530130%20VER%20X.mpg
Sensitivity of HPV Testing
http://www.digene.com/images/s
ens.gif
Study of 5,671 women age >30 years
Comparison of Various Techniques
Sensitivity
Specificity
Pap smear
60-80%
45-70%
Colposcopy
90-100%
20-50%
Digene HPV Test
80-90%
57-89%
VIA
67-79%
49-86%
Global Inequities in Cancer Prevention
United States
Reduction in Cervical Cancer Risk
100%
United States
Pap + HPV Every Year
$795,000/YLS
Pap + HPV Every 3 yrs.
$60,000/YLS
90%
United States
80%
Pap + HPV Every 2 yrs.
$174,000/YLS
15 Weeks
70%
60%
South Africa
50%
Screening 3X/Life
$250-$500/YLS
40%
South Africa
Screening 2X/Life
$50-$250/YLS
30%
20%
South Africa
10%
Screening 1X/Life
Cost saving to <$50/YLS
1,000 Years!
0%
$0
$500
$1,000
$1,500
$2,000
Lifetime Screening Cost
$2,500
$3,000
HPV Vaccine

2006:



Gardasil vaccine to prevent HPV infection was
licensed for use in girls & women ages 9-26 in
USA and 48 other countries
Protects against 2 strains of HPV responsible
for 70% of cervical cancers
Non-infectious vaccine

Made by inserting gene for protein found in
the HPV capsid into a different virus or yeast.
Recombinantly produced HPV capsid protein
self-assembles into virus like particles (VLPs).
HPV & Cervical Cancer
 Do
 Do
condoms prevent HPV?
we still need to screen
women who have been
vaccinated?
HPV Vaccine

Gardasil



Protects against new HPV infections
Not effective for women who have already
been exposed to HPV
Gardasil:



Given as a series of 3shots over a 6 months
Cost: $360
This cost is a barrier even in developed
countries, and is likely to limit its immediate
impact in developing
HPV Vaccine

HBV vaccine:




Licensed in 1981 in industrialized countries
10 yrs before used in wealthier developing
countries
>20 yrs before poorest countries had access
Difficult to achieve widespread access to a
vaccine targeted towards girls


Girls in developing countries less likely to be
in school
Gender specific immunization may be
culturally unacceptable
Summary of Cervical Cancer

Cervical cancer





Screening & Detection




2nd Leading cause of cancer death in women in world
Caused by infection with HPV
Precancercancer sequence
Precancer is very common
Pap smear; colposcopy + biopsy
Reduces incidence and mortality of cervical cancer
Insufficient resources to screen in developing countries
New technologies



Automated reading of Pap smears  reduce FN rate
HPV testing
VIA
Ovarian Cancer
Early Detection
Ovary
http://www.vacadsci.org/jsr/ovary.jpg
Ovarian Cancer

Screening:


Treatment:


No adequate screening tests available
Surgery, radiation therapy, chemotherapy
5 year survival



All stages: 53%
Localized disease (Stage I): 90%
Metastatic (Stage III-IV): 15-20%

70% of women diagnosed at these stages
Ovarian Cancer “Whispers”

Symptoms:









Unexplained change in bowel and/or bladder habits
such as constipation urinary frequency, incontinence
Gastrointestinal upset: gas, indigestion, nausea
Unexplained weight loss or weight gain
Pelvic and/or abdominal pain or discomfort
Pelvic and/or abdominal bloating or swelling
A constant feeling of fullness
Fatigue
Abnormal or postmenopausal bleeding
Pain during intercourse
Early Detection of Ovarian Cancer

Pelvic and rectal examination:



Feel uterus and ovaries to find abnormality in shape or size
Unlikely to detect early stage ovarian cancer
CA-125:




80% of women with advanced ovarian cancer have elevated CA125
Used to monitor ovarian cancer after diagnosis is surgically
confirmed - sensitive indicator of persistent or recurrent disease
Very unreliable for detecting early cancer
Very unreliable for detecting cancer in pre-menopausal women


Elevated by conditions such as pregnancy, endometriosis, uterine
fibroids, liver disease, and benign ovarian cysts
Transvaginal Ultrasound:



Use high-frequency sound waves to create pictures of ovaries
Can detect ovarian malignancies in asymptomatic women
Poor accuracy in detecting early stage disease
Performance of CA125

Overall performance in Norwegian study:



Sensitivity of 30-35%
Specificity was 95.4%
Performance by stage:


Sensitivity for Stage I cancers: 29 - 75%
Sensitivity for Stage II cancers: 67 - 100%
Transvaginal Sonography


Sensitivity = 100%
Specificity = 96%
http://www.infertilitytutorials.com/images/transvaginal_ultrasound.jpg
http://www.ivfinfertility.com/images/polycystic_ovary.jpg
Diagnostic Laparoscopy
Complication Rate =
0.5 – 1%
http://www.aiof.com/html/images/lapro.jpg
Screening Scenarios

Scenario #1:

Screen 1,000,000 women with CA125
p = .0001 (100 cancers)
 Se=35%, Sp=98.5%
 Cost = $30


Follow with laparoscopy
Complication rate = 1%
 Cost=$2,000




TP=35 FP=14,999 Complications=150
PPV =0.23% NPV =99.99%
Cost per cancer found = $1,716,200
Screening Scenarios

Scenario #2:

Screen 1,000,000 women with transvaginal US
P = .0001 (100 cancers)
 Se=100%, Sp=96%
 Cost = $150


Follow with laparoscopy
Complication rate = 1%
 Cost=$2,000




TP=100 FP=39,996 Complications=401
PPV =0.25% NPV =100%
Cost per cancer found = $300,672
Screening Scenarios

Scenario #3:

Screen 1,000,000 women >age 50 with TVUS
P = .0005 (500 cancers)
 Se=100%, Sp=96%
 Cost = $150


Follow with laparoscopy
Complication rate = 1%
 Cost=$2,000




TP=500 FP=39,980 Complications=405
PPV =1.24% NPV =100%
Cost per cancer found = $60,670
Screening Scenarios

Scenario #3 cont.:

Screen 1,000,000 women > age 50 with TVUS
P = .0005 (500 cancers)
 Se=100%, Sp=??%
 Cost = $150


How high does Sp need to be for PPV to reach
25%?

Sp = 99.985%
Does Ultrasound Screening Work?

Two studies of over 10,000 low-risk women:


The positive predictive value was only 2.6%
Ultrasound screening of 100,000 women over
age 45 would:
Detect 40 cases of ovarian cancer,
 Result in 5,398 false positives
 Result in over 160 complications from diagnostic
laparoscopy


Jacobs I. Screening for early ovarian cancer.
Lancet; 2:171-172, 1988.
Ongoing Trials

United Kingdom

200,000 postmenopausal women




United States:

37,000 women (aged 55–74)



CA 125 level plus transvaginal ultrasound examination
Transvaginal ultrasound alone
No screening
Annual CA 125 level and transvaginal ultrasound examination
No screening
Europe:

120,000 postmenopausal women



No screening,
Transvaginal ultrasound at intervals of 18 months
Transvaginal ultrasound at intervals of 3 years
http://www.mja.com.au/public/issues/178_12_160603/and10666_fm.pdf
New Screening Tool

Current screening tests look for 1 protein:





CA125
PSA
Many serum proteins
Can complex fingerprint predictive of
cancer can be identified?
PROTEOMICS:


Don’t try to understand disease mechanisms
Use proteomics to analyze patterns made by
all proteins in the blood, without even knowing
what they are
In The News
http://msnbc.msn.com/id/3933580/
New Screening Tool

Blood test to detect ovarian cancer






Examined thousands of proteins
Found a few that appear to be hallmarks of
ovarian cancer
Se = 50/50 = 100%
Sp = 63/66 = 95%
PPV = 94%
"The most important next goal is
validating the promise of these results in
large, multi-institutional trials."

Lance Liotta, M.D., Ph.D.
How do we measure serum proteins?

Mass Spectrometry:




Serum proteins are vaporized, given an
electric charge and propelled down a tube
How fast they make the trip depends on their
mass
Produces graph that shows distribution of
masses in the sample
Use computer program to analyze patterns
and distinguish blood from patients with
cancer and from those without
Typical Data
mass/charge
15,200 values of intensity vs. mass/charge
Data Analysis
Training
Validation
Useful M/Z:
534
989
2111
2251
2465
Comparative Analysis
Useful M/Z:
534
989
2111
2251
2465
OvaCheck

Quest Diagnostics and LabCorp:




Will analyze blood samples sent by doctors,
rather than sell test kits to doctors and
hospitals
Tests performed at a central location do not
require F.D.A. approval
Will be available in a few months
Cost: $100-$200
Response

Dr. Eleftherios P. Diamandis, head of clinical biochem at
Mount Sinai Hospital in Toronto.


Dr. Nicole Urban, head of gynecologic cancer research at
the Fred Hutchinson Cancer Research Center in Seattle.


"If you don't know what you're measuring, it's a dangerous
black-box technology… They are rushing into something and it
could be a disaster.“
"Certainly there's no published work that would make me tell a
woman she should get this test.“
Dr. Beth Karlan, director of gynecologic oncology at
Cedars-Sinai Medical Center


"Before you mass-market to the uninformed, fearful population,
it should be peer-reviewed,"
When asked whether she would recommend her patients not get
tested, she said: "It doesn't matter what I recommend. They are
going to do it anyway."
http://www.ovarian.org/press.asp?releaseID=263
Prostate Cancer
Early Detection
http://cwx.prenhall.com/bookbind/pubboo
ks/silverthorn2/medialib/Image_Bank/CH2
4/FG24_09a.jpg
Prostate gland contributes enzymes, nutrients
and other secretions to semen.
Prostate Cancer: Statistics

United States:




Worldwide:



230,110 new cases in US
29,900 deaths in US
2nd leading cause of cancer death in men
543,000 new cases each year
Third most common cancer in men
Risk Factors:



Age
Race (incidence 3X higher in African Americans)
Family history of prostate cancer
Risk of Prostate Cancer in Next 5 Yrs
4.5%
4.0%
3.5%
3.0%
2.5%
2.0%
1.5%
1.0%
0.5%
0.0%
<50
50-59
60-69
70-79
Current Age (Yrs)
>80
Development of Prostate Cancer

Prostate Cancer:






Slow, but continuously growing neoplasia
Preclinical form develops at age 30
Remains latent for up to 20 years
Can progress to aggressive, malignant cancer
Peak incidence: 7th decade of life
Signs and symptoms:




Often asymptomatic in early stages
Weak or interrupted urine flow
Inability to urinate
These are symptoms of prostate enlargement
Prostate Cancer (2005)

Screening (American Cancer Society recs):



Treatment:


Annual serum PSA test beginning at age 50
Annual digital rectal exam at age 50
Surgery, radiation therapy, hormone therapy,
chemotherapy
5 year survival



All stages: 98%
Localized disease: 100%
Distant metastases: 31%
What happens if DRE & PSA are +?

Biopsy of prostate ($1500)



Insert needle through wall of rectum into prostate
Remove fragments of prostate
Examine under microscope
http://my.webmd.com/NR/rdonlyres/055
7C509-969D-4441-A7BE1236F9623C2F.jpeg
Rx for Localized Prostate Cancer

Radical prostatectomy (remove prostate)


Usually curative
Serious side effects:
Incontinence (2-30%)
 Impotence (30-90%)
 Infertility


Conservative management

Just watch until symptoms develop
Does Early Detection Make a D?

10 Yr Survival Rates for Localized Prostate CA:

Grade I:
Surgery 94%
 Conservative Rx 93%


Grade II:
Surgery 87%
 Conservative Rx 77%


Grade III:
Surgery 67%
 Conservative Rx 45%


Makes a difference only for high grade disease
Challenges of Screening

Prostate cancer is a slow-growing cancer




Not symptomatic for an average of 10 years
Most men with prostate cancer die of
other causes
Treatment has significant side effects
50 year old man:



40% chance of developing microscopic
prostate cancer
10% chance of having this cancer diagnosed
3% chance of dying of it
Should we screen?

Yes:




Localized prostate cancer is curable
Advanced prostate cancer is fatal
Some studies (not RCTs) show decreased
mortality in screened patients
No:


False-positives lead to unnecessary biopsies
Over-detection of latent cancers


We will detect many cancers that may never have
produced symptoms before patients died of other
causes (slow growing cancer of old age)
No RCTs showing decreased mortality
Clinical Evidence

Three case-control studies of DRE


Mixed results
One completed RCT of DRE & PSA

Found no difference in # of prostate cancer
deaths between groups randomized to
screening and usual care
Randomized Clinical Trials Underway



Prostate Cancer vs. Intervention Trial (US)
Prostate, Lung, Colorectal and Ovarian
Cancer Screening Trial (US)
European Randomized Study for Screening
for Prostate Cancer



239,000 men
10 countries
Will be complete in 2008
Do All Countries Screen with PSA?

United States:


Conflicting recommendations
Europe:


No
Not enough evidence that screening reduces
mortality
Conflicting Recommendations in US

Guide to Clinical Preventive Services


American College of Preventive Medicine


Do NOT screen using DRE or serum PSA
Men aged 50 or older with >10 yr life
expectance should be informed and make
their own decision
American Cancer Society (and others)

Men aged 50 or older with > 10 yr life
expectancy should be screened with DRE and
serum PSA
PSA Test
Details
The PSA Test

What is PSA?





Prostate-specific antigen
A glycoprotein responsible for liquefaction of semen
Highly specific for prostate (only made by the prostate)
PSA test is a blood test to measure PSA levels
Why measure PSA to screen for cancer?

PSA levels are closely (but not definitively) associated
with prostate cancer



May be elevated in benign conditions (BPH, Prostatitis)
Not always high in cancer
Cost:

$30-$100
PSA Levels

Normal PSA Levels:


< 4 ng/ml
Can vary by age
40-49
 50-59
 60-69
 70-80


yo
yo
yo
yo
<
<
<
<
2.5
3.5
4.5
6.5
ng/ml
ng/ml
ng/ml
ng/ml
Cancer Patients:



20-25% have PSA < 4 ng/ml
20-25% have 4 ng/ml < PSA < 10 ng/ml
50-60% have PSA > 10 ng/ml
Sensitivity and Specificity of PSA

How to determine

Trial: Serum PSA  Biopsy (Gold standard)





If BX
If BX
If BX
If BX
BUT:





is positive and PSA is positive: get TP
is positive and PSA is negative: get FN
is negative and PSA is negative: get TN
is negative and PSA is positive: get FP
if BX is negative:
Did BX just fail to sample area with cancer?
Hard to calculate Specificity - TN/(TN+FP)
Cutpoint of 4 ng/ml
Sensitivity = 63-83%
Specificity = 90%
Predictive Value Calculation

Screening Performance:


Number Tested:





N=1,000,000; Prevalence = 2%
Costs:


Se = 73%; Sp = 90%
Screening = $30; Follow up biopsy = $1500
What
What
What
What
are PPV & NPV?
is screening cost?
is biopsy cost?
is cost/cancer found?
PSA Example – Predictive Value
Disease
Present
Disease
Absent
Test
Positive
14,600
Test
Negative
5,400
98,000
882,000
# Test Pos # Test Neg
= 112,600 = 887,400
# with Disease =
20,000
#without Disease
= 980,000
Total Tested =
1,000,000
PPV =14,600/112,600 = 13%
NPV =882,000/887,400 = 99%
PSA Example – Cost
Disease
Present
Disease
Absent
Test
Positive
14,600
Test
Negative
5,400
98,000
882,000
# Test Pos # Test Neg
= 112,600 = 887,400
# with Disease =
20,000
#without Disease
= 980,000
Total Tested =
1,000,000
Cost to Screen =$30*1,000,000+$1500*112,600 =$168,900,000
Cost/Cancer = $168,900,000/14,600=$13,623
Health – Policy Space
Health
Improves Health
Saves Money
Vaccines
Worsens Health
Saves Money
Improves Health
Costs Money
Most Interventions
$$$
Worsens Health
Costs Money
??????????????????
http://www.npr.org/templates/story/story.p
hp?storyId=93313794
New Technologies: Improved Screening

Additional serum markers Improve Sp




Free PSA
PSA density
PSA velocity
Predict those cancers which will progress
to advanced disease

Gene chips
Cancer Screening Exams

Cellular Changes


Serum Proteins




Pap smear
PSA
CA125
OvaCheck
Genetic Changes


HPV DNA
Mutations in the BRCA1, BRCA2 genes  Risk

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